Lens and Cataract

CATARACTBy: Zichri Keren O. Perocho

MHAM Senior Clerk

Greek word katarraktes (down-rushing; waterfall)

The lens -transparent, avascular,

biconvex structure held in position by the ciliary zonules (of Zinn).

-very rich in proteins (35% w/w),mostly beta-crystallins, the insoluble portion (albuminoid) of which increases with age contributing to cataract formation

-metabolism is mainly anaerobic, glucose and nutrients from post. Chamber aqueous humor

• Subluxation of the lens in a patient with Marfan's syndrome.

• derived from surface ectoderm• -continues to grow throughout life.• Birth: 6.4mm equatorially, 3.5 mm AP

wt: 90 mg• Adult: 9 mm equatorially, 5 AP

wt: 255 mg- Relative thickness of cortex increases with

age

FUNCTIONS

• Functions: _ to maintain its own clarity

– to provide refraction (2nd refracting unit)(15-20 D)

– Accommodation (inherent elasticity)

Lens

Lens: layersFrom anterior to posterior :- Capsule : BM of the anterior

epithelium (thickest BM in body)

- ant. epithelium: single row of cuboidal cells responsible for metabolism of the whole lens

- ant. Cortex (AC)- central nucleus (N)- posterior cortex (PC)- posterior capsule

-Lens capsule / epithelium

-Lens cortex lies between epithelium and nucleus (anterior and posterior!); thickens with age

- Nucleus-Adult nucleus -Fetal nucleus -- secondary lens fibers formed in utero -Embryonic nucleus -- dark crescent shaped area in very center of lens; primary lens fibers formed in utero

Definition: any opacity of the lens that may or may not be associated with visual problems and manifest as an obstruction of the red orange reflex on funduscopy

GENERAL SYMPTOMS• Visual impairment not associated w/ pain or

inflammation• Blurred vision; distorted vision• Monocular Diplopia (lens opacity in the visual axis

that splits bundles of light )• Glare (eye discomfort & depression of central vision produced

when a bright light enters a field of vision esp. when eye is adapted to

dark ) • altered color perception

history

• - injury (traumatic: metallic foreign body: iron & copper/ contusion)

• - age• - steroid use? BA?• Toxins• DM?• Systemic d/o? e.g. hypocalcemia,

myotonic dystrophy, skin disease

Normal lens / Cataractous lens

Clear lens / Cataractous lens

Visual image without a cataract

Visual image with a cataract:there are gray areas and partial loss of image perception. Color perception is

different

• Decreased V.A

Physical examination

In family practice, funduscopy visual acuity testing and pinhole should be done for all patients suspected to have cataract.

For patients suspected of having cataract, slit lamp examination, dilated funduscopy and tonometry should routinely be done in

ophthalmologic practice.

Mature lens opacities can be diagnosed with the unaided eye by the presence of a white pupil

(leukocoria).

Retroillumination of the lens (Brückner’s test) - quickest preliminary examination method for lens opacities

- Under a light source or ophthalmoscope (set to 10 diopters), opacities will appear black in the red pupil

2. The lens can be examined in greater detail and in three dimensions under focal illumination with a slit lamp with the pupil maximally dilated. The extent, type, location, and density of opacities and their relation to the visual axis can be evaluated. CA

Where the fundus is not visible in the presence of a mature lens

opacity, ultrasound studies (one-dimensional A-scan and

two-dimensional B-scan studies) are indicated to

exclude involvement of the deeper structures of the eye.

Methods of Classifying Cataract

I. According to AGE at Onset A. Congenital D. AdultB. Infantile E. senile C. Juvenile (RS) (congenital vs acquired)

II. According to location of Opacity in lens

A. Nuclear C. Subcapsular: PosteriorB. Cortical

III. According to degree of opacity present

A. Immature/IncipientB. MatureC. Intumescent/ SwollenD. Hypermature/ MorgagnianE. After- Cataract

IV. According to Rate of development

A. Stationary B. Progressive

V. On basis of Biomicroscopic appearance

A. Lamellar C. Punctate and many B. Coralliform others

VI. On basis of CAUSE A. With systemic DisordersB. Without Systemic Disorders

Cataract w/ Systemic Disorders

I. Generalized A. Embryopathies (induced in utero): Maternal infxn (Rubella); maternal drug ingestion, radiationB. Marfan syndrome (arachnodactylyl, ectopia lentis, mesodemal hypoplasia)

C. Retinal Pigment epithelium degenerationsD. Systemic infxns causing uveitis w/ complicatedcataract

II. Cutaneous Atopic Dermatitis; Rothmund Syndrome; Incontinentia pigmenti (Werner); Congenital ichthyosis ; Siemen Syndrome

III. Metabolic DM; Galactosemia; Lowe syndrome; Hypocalcemia; Fabry disease; Refsum disease; G6PD deficiency; Inc. Plasma Tryptophan

IV. Neurologic Hepatolenticular degeneration (sunflower cataract); Spinocerebellar ataxia, oligophrenia

V. Muscular Myotonic dystrophy

VI. Osseous Mandibulofacial dysostosis; Osteitis fibrosa & skin pigmentation; stippled epiphysis; oxycephaly

VII. Chromosomal abnormalities

Down syndrome; 13-15 trisomy; Cockayne syndrome

Cataract without Systemic D/O

I. Eye otherwise healthy & No systemic Disease

A. Nearly all Aging CataractsB. Most Cataracts in adultsC. Many hereditary and Congenital cataracts

II. Cataract Combined w/ other Ocular d/o but no systemic abnormalities

A. Congenital and hereditary abnormalitiesB. Acquired defects and delayed hereditary abnormalities 1. Miscellaneous ocular ds (glaucoma. Uveitis…) 2. Retinopathy of Prematurity(cataract develop after 3 y.o. 3. Toxicity(Corticosteroid, ergot, naphthalene, topical

anticholinesterase, phenothiazines, dinitrophenol, triparanol)

4. Ocular trauma: a. Contusion (Vossius ring), posterior subcapsular

cataract b. Laceration c. Retained Intraocular foreign body (iron, copper) d. electromagnetic radiation: Infrared; Microwaves;

Ionizing radiation; UV radiation e. Anterior ocular ischemia after Retinal detachment

surgery

NO CLASSIFICATION OF CATARACT IS SATISFACTORY

The Clinically Significant Points include1. Severity of Visual Impairment2. Likelihood of visual improvement after

Cataract extraction3. Presence of Systemic disease and if present,

whether the disease is related to the cataract development

4. Local Ocular Causes in the absence of systemic disease.

Congenital Cataracts

Hereditaryearly embryonic

(transplacental) damage

Age Related/Senile Cataract

Framingham, massachusetts study:

Age related cataract were likely to have:

1. inc. serum phospholipid2. High non-fasting blood

glucose levels3. High blood pressure

MORPHOLOGIC CLASSIFICATION:

1. Nuclear Sclerosis/ hard cataract- “second sight”

2. Cortical/ Soft Cataract- “spoke-like pattern

3. Posterior Subcapsular opacity: MC ; appear as gold & white granules

2 fundamental processes

1. lens cortex – imbalance in electrolytes leading to the overhydration of the lens resulting in the liquefaction of the lens fibers.

2.lens nucleus – modification of lens protein, leading to its aggregation. A pure nuclear cataract shows very little change in electrolyte content. Protein aggregation leads to large particles creating a light scattering centers

Cataracts

Nuclear cataract- located in the lens nucleus (N)

Anterior cortical cataract/anterior cataract- located in the anterior portion of the cortex (AC

Posterior cortical cataract/posterior cataract - located in the posterior portion of the cortex (PC)

Equatorial cortical cataracts/equatorial- cataracts periphery of the lens (EC)

ACC. Degree of OPACITY/ Stage of Cataract Devn’t

1. IMMATURE/ INCIPIENT- slightly opaque

2. MATURE/moderately advanced- completely opaque

3. INTUMESCENT/ SWOLLEN- water content is maximal and lens capsule is stretched

4. HYPERMATURE/FAR-ADVANCED/ MORGAGNIAN- water has escaped from the lens, leaving a relatively dehydrated very opaque lens and wrinkled capsule

Morgagnian cataract. A free-floating nucleus can be seen at the bottom of the lens.

“sunset appearance”

Base on Biomicroscopic appearance

A.Lamellar B. Punctate- a very small cataract

confined to a specific location referred to as a "punctate" cataract.

C. Coralliform

20/20-20/25

20/40- 20/50

20/200

METABOLIC CATARACT Diabetes mellitus

- (Type 2 DM) Senile cataract –appears earlier (2–3 years earlier.) and progresses faster than non diabetic

True Diabetic cataract (poorly controlled

Growth onset DM)– result of osmotic overhydration of the lens; appears as bilateral white punctate or radial snowflake pattern of cortical opacities (snowflake cataract)

True diabetic cataract : white punctate or radial snowflake pattern of cortical opacities (snowflake cataract) The opacities are

bilateral and cortical predominantly the anterior and posterior subcapsular region

Toxic CATARACT

Galactosemia• AR ; An inborn error of metabolism

resulting in severe impairment of galactose utilization; caused by an absence of an enzyme galactose-1-phosphate uridyl transferase (GPUT), Galactokinase--- inc galactose alcohol (dulcitol). Galactosemic cataract is the only form of cataract that responds to conservative therapy.Main feature: central oil droplet cataract

“Oil droplet” appearance of a pure nuclear cataract seen on retroillumination examination.

Galactokinase deficiencyAR; deficiency of the first enzyme in the metabolic pathway; main feature is lamellar cataract.

MannosidosisDeficiency of α mannosidase leading to the accumulation in the tissues of mannose-rich oligosaccharides. Spoke like posterior capsular cataract is common.

• Spoke-like ( wheel ) posterior capsular cataract.

Fabry’s DiseaseX linked recessive, spoke like cataracts in 25% of cases with cornea virticillata

 Lowe’s syndrome

Oculocerebrorenal syndrome ;an inborn error of amino acid metabolism with congenital glaucoma as part of the main feature.

Cortical dot opacities in a Lowe's disease (oculocerebrorenal syndrome) carrier.

Corticosteroids -- PSC may form following topical (more rare) or oral (more common) use of corticosteroids. Cataract looks exactly like age-related PSC. Dose-dependent.

Other drugs – Miotics(anticholinesterase) phenothiazines, gold salts, amiodarone, allopurinol may cause cataracts and deposition of the drug in the lens or on lens capsule (corneal deposits also common with some drugs)

TRAUMATIC CATARACT:

MC cause of unilateral cataract in young individuals. It may be caused by one of the following:

1. Direct penetrating injury to the lens.2. Concussion which may lead to Vossius

ring resulting from an imprinting of the iris pigment onto the Ant. lens capsule

3. Electric shock and lightning which are rare causes

4. Ionizing irradiation to ocular tumors

Posterior subcapsular

Trauma

• Usually unilateral, usually rosette-shaped cataract following any sort of trauma to the eye (blunt trauma, excessive heat and cold, electric shock, radiation, concussion, perforating injuries, intraocular foreign bodies esp. iron & copper).

• Can be lamellar. • A VOSSIUS RING is deposition of iris pigment

on the front of the lens capsule usually following blunt trauma.

Traumatic cataractstellate opacity in the nucleus, seen on retroillumination

(Brückner’s test) examination after a blunt trauma.

Radiation-induced cataract glassblower’s cataract

MANAGEMENT

• Medical TreatmentIn spite of theoretical approaches in animal research,

the effectiveness of conservative cataract treatment in humans has not been demonstrated.

At present, no conservative methods are available to prevent, delay, or reverse the development of a cataract. Galactosemic cataracts are the only exception to this rule.

Surgical ManagementCataract surgery is the most frequently performed

procedure in ophthalmology.Objective of management of cataract: a) correction of visual impairment b) maintenance of quality of life and c) prevention of progression.

INDICATIONS FOR SURGERY:

1. When the cataract causes a visual defect that interferes with an individual’s vocation

2. when the lens threatens to cause a Secondary glaucoma or uveitis

3. permit visualization of the fundus in order to monitor glaucoma

4. permit adequate visualization of the fundus before photocoagulation, vitrectomy, or retinal surgery

Indication for surgery (CPG)

a) patient’s preference and needs, b) functional disabilityc) cataracts with concomitant ocular problems

CATARACT SUGERY

ICCE       ECCEPhacoemulsification

Pre-operative evaluation• The degree of reduction of vision due, at least in large part, to the

cataract should be evaluated. R/O sight-threatening diseases, such as age-related macular degeneration or glaucoma, (less improvement)

• The eyes should have a normal pressure, or any pre-existing glaucoma should be adequately controlled on medications. Uncontrolled glaucoma: combined cataract-glaucoma procedure (Phaco-trabeculectomy)

• The pupil should be adequately dilated using eyedrops; not adequate: mechanical pupillary dilatation may be needed during the surgery.

• The patients with retinal detachment may be scheduled for a combined vitreo-retinal procedure, along with PC-IOL implantation.

•

ICCE- Intracapsular cataract extraction (ICCE) involves the removal

of the lens and the surrounding lens capsule in one piece. 1930-1980

- requires an incision of nearly 180 degrees at the superior corneoscleral limbus, w/c must be closed with a number of interrupted suture (high rate of complications due to the large incision required and pressure placed on the vitreous body)

- largely superseded and is rarely performed in countries where operating microscopes and high-technology equipment are readily available.

- After lens removal, an artificial plastic lens (an intraocular lens implant) can be placed in either the anterior chamber or sutured into the sulcus.

Cryoextraction is a form of ICCE that freezes the lens with a cryogenic substance such as liquid nitrogen

- cataract is extracted through use of a cryoextractor — a cryoprobe whose refrigerated tip adheres to and freezes tissue of the lens, permitting its removal.

Although it is now used primarily for the removal of subluxated lenses, it was the favored form of cataract extraction from the late 1960s to the early 1980s

ECCE

- Conventional extracapsular cataract extraction (ECCE): involves the removal of almost the entire natural lens while the elastic lens capsule (posterior capsule) is left intact to allow implantation of an intraocular lens.

- involves manual expression of the lens through a smaller incision made in the cornea or sclera. Valve type incision

- indicated for patients with very hard cataracts or other situations in which phacoemulsification is problematic. Microincision cataract surgery involves a technique by which a cataract can be reached through an incision of 1.5 millimeters or less.

• ECCE w/ P C IOL

PhacoemulsificationPhacoemulsification (Phaco) is the preferred method in most

cases. (3mm incision) - involves the use of a machine with an ultrasonic handpiece

equipped with a titanium or steel tip. The tip vibrates at ultrasonic frequency (40,000 Hz) and the lens material is emulsified.

- A second fine instrument ("cracker" or "chopper") may be used from a side port to facilitate cracking or chopping of the nucleus into smaller pieces. Fragmentation into smaller pieces makes emulsification easier, as well as the aspiration of cortical material (soft part of the lens around the nucleus).

- a dual irrigation-aspiration (I-A) probe or a bimanual I-A system is used to aspirate out the remaining peripheral cortical material.

Operative procedures1. Anesthesia (topically or via injection next to (peribulbar) or behind

(retrobulbar) the eye)2. Exposure of the eyeball using a lid speculum,3. Entry into the eye through a minimal incision (corneal or scleral)4. Viscoelastic injection to stabilize the anterior chamber and to help

maintain the eye pressurization5. Capsulorhexis (removal of anterior lens capsule)6. Hydrodissection pie7. Hydro-delineation8. Ultrasonic destruction or emulsification of the cataract after nuclear

cracking or chopping (if needed), cortical aspiration of the remanescent lens, capsular polishing (if needed)

9. Implantation of the, usually foldable, intra-ocular lens (IOL)10. Viscoelastic removal11. Wound sealing / hydration (if needed).

• Phacoemulsification

IOLIntraocular lens implantation: After the removal of the

cataract, an intraocular lens (IOL) is usually implanted into the eye, either through a small incision (1.8 mm to 2.8 mm) using a foldable IOL, or through an enlarged incision, using a PMMA (polymethylmethacrylate) lens.

- made of silicone or acrylic material of appropriate power is folded either using a holder/folder, or a proprietary insertion device provided along with the IOL.

- The lens implanted is inserted through the incision into the capsular bag within the posterior chamber (in-the-bag implantation).

• Phacoemulsification

IOL1. Monofocal lens: MC , are in sharpest focus at only one distance; do

not correct pre-existing astigmatism; only one specific focus (far or near)

2. Toric lens: more power in one specific region in the lens to correct astigmatism as well as distance vision. While toric lenses can improve distance vision and astigmatism, the patient still will require corrective lenses for all near tasks, such as reading or writing.

3. Multifocal lens: one of the latest advancements in lens technology; have a variety of regions with different power that allows some individuals to see at a variety of distances, including distance, intermediate, and near. - - cause significantly more glare than monofocal or toric lenses.

- cannot correct astigmatism, and some patients still require spectacles or contact lenses for clearest vision.

COMPLICATIONS1. PVD - Posterior vitreous detachment- accompanied by peripheral light

flashes and increasing numbers of floaters2. Posterior capsular opacification ( after-cataract): Nd-YAG laser

(neodymium-yttrium-aluminum-garnet) to disrupt and clear the central portion of the opacified posterior lens capsule (posterior capsulotomy).

3. Posterior capsular tear- 2-5%4. Retinal detachment5. Toxic Anterior Segment Syndrome or TASS is a non-infectious

inflammatory condition that may occur following cataract surgery. It is usually treated with topical corticosteroids in high dosage and frequency.

6. Endophthalmitis is a serious infection of the intraocular tissues7. Glaucoma may occur and it may be very difficult to control. It is usually

associated with inflammation, specially when little fragments or chunks of the nucleus get access to the vitreous cavity.

8. macular edema9. pseudophakic bullous keratopathy (anterior chamber lenses- damage

ce)

THANK YOU AND THANK YOU AND GOD BLESS!!!GOD BLESS!!!